Ingot mold plug



Aug. 22, 1939. A. c. ESTEP INGOT MOLD PLUG Original Filed Sept. 3, 1937Enventor attorneys Patented Aug. 22, 1939 INGOT MOLD PLUG Arthur C.Estep, Waynesburg, Ohio, assignor to The Whitacre-Greer FireproofingCompany, Waynesburg, Ohio, a corporation of Ohio Application September3, 1937, Serial No. 162,315

. Renewed May 25, 1939 Claims. 01. 22-148) ingot mold; that is, a moldhaving an open top with side walls gradually diverging from the bottomtoward the top. A tapered hole is provided at the bottom of the moldwhich is closedby a sealing plug while the ingot is poured and theingot, after cooling, is forced upwardly out of the mold. Prior topouring the ingot the plug referred to is forced into the hole at thebottom of the mold which hole is tapered according to the acceptedpractice so that the plug may be driven into the hole and have a snugfit which prevents the escape of molten metal during the pouring of theingot. Because of its ability to accommodate itself to the contour ofthe hole at the base of the ingot mold as by limited surface crushing orabrasion against the wall of the hole, an ingot mold plug formed ofburned clay is capable of effecting an efficient seal. The presentinvention relates principally to an improved refractory ingot mold plug,and the method for making same.

It is among the objects of my invention to provide a burned clay ingotmold plug and method of .making the same whereby the plug will anwithstand the shock to which it may be subjected while being driven intothe tapered hole of the ingot mold and will withstand the thermal andphysical shock occasioned by the flow of molten metal into the mold.Another object is to provide a refractory plug which will not spawl inthe area of contact with molten steel or otherwise give offnon-metallics to the ingot. It is a further object of my invention toprovide a method of making an ingot mold plug which will 4 give in thefinished plug certain structural characteristics of yielding strengthwhereby to resist deleterious fracture or spawling in use. It is also anobject of my invention to provide an ingot mold plug with circularconcentric laminations which will tend to restrict any fracture of theplug to the direction defined by the laminations. It is a further objectof my invention to provide a method of making an ingot mold plug inwhich an extruded clay tile cylinder is upset to form a plug having atruncated cone shape. It is a further object of my invention to providean apparatus for carrying out the method for making the article inaccordance with the preceding objects. It is a further object of my in-55 vention to provide an apparatus for upsetting a ceding object.

cylindrical clay slug into a truncated conein which means are providedto compensate for variations in slug volume. It is a further object ofmy invention to provide a burned clay mold plug characterized by smoothtroweled outer sur- I faces especially resistant to spawling andcracking.- It is also among the objects of my invention to provide amethod and apparatus for making a mold plug in accordance with the pre-Further objects and advantages relating to economies of manufacture andcharacteristics of the finished mold plug will appear from the followingdescription and the appended drawing in which:

Figure 1 is a view of a clay extrusion apparatus suited to extrudelaminated cylindrical stock employed in my invention;

Figure 2 is a sectional view with parts broken away of an upsetting ormolding apparatus made according to my invention; 20

Figure 3 is an enlarged sectional view of the relief mechanism employedin the upsetting or molding apparatus;

Figure 4 is a transverse sectional view (taken along the line 4-4 ofFigure 5) of a mold plug constructed according to my invention;

Figure 5 is a plan view of the mold plug;

Figure 6 is a partial sectional showing of a mold plug according to myinvention arranged within an ingot mold.

The first step in forming a mold plug corresponding generally to theobjects outlined above comprises extruding wet clay stock of round crosssection such as l in Figure 1. Preferably the clay stock is extrudedfrom an auger machine 5 of the type in which the mass of wet clay beingextruded is open to the atmosphere through a hopper as at 8 tofacilitate the formation of laminations in the extruded stock 4. Thereis a tendency for extruded clay products to form laminations generallyparallel to the walls of the extrusion die and in forming certainarticles it is conventional practice to extrude from a chambermaintained at less than atmospheric pressure to prevent the formation oflaminations. According to my invention, however, I prefer to takeadvantage of the laminating tendency referred to and therefore preferthat there be little or no deaerating of the extruded mass. In additionto insuring against deaerating the mix should 60 be sufficiently shortso that marked circular concentric laminations coaxial of the stock willbe formed in portion 4. The clay may be fed to the auger machine 5 froma pug mill 1 in the usual manner and forced by an auger through theextruded stock 4 is severed by wire cutters or other suitable means intoshort cylindrical slugs 6 having a volume corresponding substantially tothe volume of a finished mold plug.

Subsequent to the extrusion of the clay sto 4 and thecutting thereof toprovide cylindrical slugs 6, the slugs are each transferred while in aplastic condition to an upsetting apparatus arranged to upset thecylindrical slug into a plug having a truncated cone shape. In Figure 2I have illustrated a preferred form of upsetting apparatus in which apair of cylindrical bores l9 and 26 are joined to each other by atapered wall portion 2| which corresponds sulntantially to the shape ofthe finished mold plug. A backup or ejector plunger 24 is positionedwithin the bore IS to close the lower end of the upsetting chamber andthe upsetting plunger 26 is arranged within the bore 20 so that it maybe moved to close the opposite side of the mold plug chamber. I haveshown in the dotted lines of Figure 2 a cylindrical mold plug blank 6 aspositioned prior to its upsetting and the upset mold plug 30 resultingfrom the movement of the plunger 26 to its position shown fills the moldplug chamber.

-- resistant covering resulting from upsetting the slug .as abovedescribed may be further'improved by effecting a troweling action uponthe outer surface of the slug during and/or after the upsetting. Thetroweling or wiping of the outer surface is preferably accomplished byrotating the plunger 26 and such rotation ispreferably effected so as toaffect no disturbance of the lami-' nated structure within the body ofthe plug. The rotation of the plunger 26 may be accomplished by havingthe plunger shaft splined axially as at 43 so that the shaft mayreciprocate within an internally splined worm gear 4| supported by abracket 40. A spur gear 42 is arranged to mesh with and drive the wormgear 4|. The rotation of the plunger 26 during and/or after theupsetting of the slug appears to efiect a troweling of the surface whichforces water and minute clay particles to the outer surface of the plug,Upon burning the smooth-troweled outer surface of the plug acquires ahard, tough, skinlike cover which is resistant to spawling and thuscontributes to the prevention of non-metallics being carried up into theingot during the pouring thereof.

Due to the fact that as a practical matter in commercial production itis difilcult or impossible to obtain a series of cylindrical slugs 6which are of exactly the same volume and due to the fact that suchplastic slugs are more or less incompressible, it would, in the absenceof an apparatus such as I have provided, be difllcult to obtain moldplugs completely shaped and filled. Because of the variation in volumeof the cylindrical slugs and because it is desired to produce truncatedcone shaped mold plugs of uniform height and full body, I have providedan upsetting apparatus which will compensate for the normal variationsin the volume of the cylindrical slugs.

Preferably the back-up or ejector plunger 24 is centrally apertured asat 26 (Figure 3) and carries in said aperture a piercing tool 21 whichis normally urged upwardly to the limit of a slot space between the twoplungers 24 and 26. When the plastic slug 6 is forced downwardly intothe upsetting chamber defined by the two .plungers and the tapered wall2|, it will be observed that the piercing tool 21 is forced into theplastic mass and that the plastic slug offers a resistance to themovement of the plunger 26 until it has reached the end. ofthecylindrical bore 20 as shown. As the plunger 26 approaches the positionshown it will be understood that the hydrostatic pressure in the slugbeing upset will force the piercing tool 21 downwardly out of theupsetting chamber against the resistance of the spring 29. The distancewhich the piercing tool is forced downwardly out of the upsettingchamber by the hydrostatic pressure in the plastic slug will depend uponthe difference in volume between the cylindrical slug and thevolume-defined by the. tapered wall 2| and the plungers 24 and. 26 intheir positions shown in Figure 2. It is possible according to the knownmethods of cutting plastic clay stock to cut cylindrical slugs in whichthe volumes will not vary with respect to each other more than thevolume of the piercing tool 21 in its raised position. Thus it ispossible with the usual known methods of wire cutting wet clay stock andthe method and apparatus I have provided for upsetting such stock toobtain mold plugs having a truncated cone shape and having a uniformheight and otherwise being uniform in their external dimensions.

The steps which include the cutting and updistinguishable fromeach otherby laminations such as l6 shown in Figure 4. Subsequent to the upsettingas described in connection with Figures 2 and 3 the plastic mold plug isburned in the conventional manner and the resulting laminated upset andburned plug 32 is shown in Figures 4 and 5.

The finished plug may be inserted through the open end of an ingot mold36 and driven into the base of the ingot mold to close the opening 36therein as shown in Figure 6.- Ordinarily an ingot mold plug of thistype is forcibly wedged into the opening 36 by driving and jarringoperations effected with a heavy timber or the like reciprocated fromthe open end of the ingot mold. The impact at the upper surface of theplug may be 'suflicient to effect a,s1ight abrasion or surface fractureof the conical walls of the ceramic mold plug so that the plug willacquire substantially the shape of the aperture 26 to which it is fittedand form a tight seal against the molten metal poured into the mold.

It will be observed that even though the impact of a heavy timber suchas is required to force the plug into the mold opening 26 be such aswould break or fracture the plug, the truncated laminations defined bysurfaces l6 tend to permit the plug sections between said surface toslip with respect to each other. It is possible is fractured two orthree times on different concentric conical surfaces' 16 and yet itsutility as a mold plug will be preserved. It will also be understoodthat such plug fracture caused by internal stresses within the pluggrowing out of the burning and shrinkage will be more or less confinedto the surfaces I6 and that regardless of the cause of plug fracture theusefulness of the plu is not destroyed as long as the fracture isrestricted to concentric surfaces such as l6.

Among the desirable characteristics of a burned clay mold plug is theresistance of the plug to spawling at the surface due to the thermalshock caused by the inflowingmolten metal as the mold is being poured. Aresistance to sp awling or surface fracture is desired in that there isa tendency for the molten metal to float broken or spawled particles ofthe plug and carry the same up into the ingot. An ingot carryingparticles of nonmetallic is obviously defective for rolling purposes. Itwill be observed that due to the laminations or curved fracture surfacessuch as Hi the thermal expansion caused by the sudden inflow of moltenmetal is broken up or limited by its action by the fracture surfaces "5.The surfaces l6 appear to prevent a heat flow across the upper surfaceof the plug such as would be suflicient to break away the top layer ofthe plug from the body of the plug, While it is difficult to determineall of the reasons why a mold plug having concentric laminations is.especially resistant to spawling or surface fracture during the pouringof the ingot I have found that mold plugs having such laminations doresist surface spawling to a marked degree.

Although I have illustrated and described certain specific forms inwhich my invention may be practiced, various changes and modificationswill occur to those skilled in the art, all within the precepts of myinvention, and I do not care to be limited to the precise embodimentsherein particularly described or in any manner other than by the claimsappended hereto when construed with the range of equivalents to which Imay be entitled in view of the prior art.

.I claim:

1. A mold plug having a truncated cone shape and a plurality ofconcentric laminations extending axially of the mold plug.

2. A burned clay mold plug having concentric circular laminationsproviding concentric fracture surfaces whereby upon mold plug fracturealong such surfaces one portion of the mold plug may slip telescopicallyalong said fracture surfaces.

3. A burned clay mold plug resistant to surface fracture due to thermalshock comprising a plurality of concentric portions telescopicallynested one within the other with the edges of said portions terminatingon the upper face of the plug normally subjected to thermal shock.

4. A burned clay mold plug formed by plastic extrusion in the directionof its axis, upsetting to the form of a truncated cone along the sameaxis, drying and burning, having throughout itsbody conical laminationswhose axes substantially correspond to the axis of the exterior conicalsurface thereof, the larger circular surface of said plug having beenwiped or pressed while wet comprising a smooth hardened skinresistant'to abrasion.

5. A burned clay ingot mold plug formed by plastic extrusion in thedirection of its axis and upset to form a truncated cone along the sameaxis and dried and burned, and adapted to be disposed in the conicallytapered bottom hole of an ingot mold with its upper surface exposed tothe fluid metal contents of the mold, said plug comprising a solidunitary laminated structure having cohering laminations throughout itsbody lying substantially normal to said exposed upper surface andconstraining the tendency to fracture to the directions of saidlaminations, the said upper surface of said plug having been wiped orpressed while wet, and comprising a smooth hardened skin containing theends of said laminations and resistant to abrasion.

ARTHUR C. ES'I'EP.

